NCDC added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.

National Overview

Based on the Palmer Drought Index, severe to extreme drought affected about 15 percent of
the contiguous United States as of the end of June 2008, an
increase of about 7 percent
compared to last month. By contrast, about 16 percent of the
contiguous U.S. fell in the severely to extremely wet
categories.

Historical temperature, precipitation, and Palmer drought data
from 1895 to present for climate divisions, states, and regions in
the contiguous U.S. are available at the Climate Division:
Temperature-Precipitation-Drought Data page in files having
names that start with "drd964x" and ending with "txt" (without the
quotes).

Detailed Drought Discussion

The weather pattern during June was a
continuation of the pattern of the last several months. A series of
cold upper troughs over the northwestern U.S. at the jet stream
level propagated low pressure
systems and cold fronts, with heavy rain and severe weather,
across the Midwest to Northeast. Dry, warm high pressure dominated
at the upper levels across the southern states. The result was wet
weather and flooding from the central Plains to the Great Lakes,
with drought conditions improving in the northern Plains. Dry
weather prevailed in the south, especially over the Southwest,
southern
Plains, and Southeast,
where drought conditions deteriorated this month (July 1 USDM
versus May
27 USDM).

Drought expanded in the West during June, with USDM statistics
showing moderate to extreme drought growing to 35% of the
region by the end of the month compared to 26% a month ago.
California had the fourth
driest June and driest
March-June in the 1895-2008 record. The California dryness was
so severe that Governor Schwarzenegger declared the first statewide
drought in 17 years. According to media reports, the last time a
statewide drought was declared in California was 1991. Numerous
lightning-sparked wildfires were burning across the state by the
end of the month.

Hot
and dry
conditions expanded drought in the southern Plains, with the
hardest-hit areas being southern
Texas and the area centered around the western
part of the Oklahoma panhandle. Drought was having some severe
localized impacts in the Oklahoma panhandle. According to media
reports (The Oklahoman, 6/13), impacts included large-scale
livestock sell-offs, wildfires, and growing risk of significant
dust storms. In Cimarron county, Oklahoma, the wheat crop was
nonexistent this year, pastures were dormant or dead, and wind
erosion of the soil was occurring — according to old-timers
in the area — like back in the Dust Bowl days. Governor Henry
requested federal disaster aid in June for Oklahoma farmers and
ranchers who have been hit by drought and extreme weather
conditions in nine northwest counties. Southern Texas (climate
division 9) experienced the driest
October-June in the 114-year record. According to media
reports, Texas agricultural specialists feared record losses in
agriculture this year due to heat and drought conditions combined
with skyrocketing input costs. Cotton producers in southern Texas
have already lost nearly their entire crop.

According to the Southeast
Regional Climate Center, Florida, Puerto Rico and the
Washington, D.C. area were all relatively wet during the month,
with precipitation a few percent above normal. Most other areas
were below normal. However, precipitation came almost exclusively
from widely scattered showers. There was not a day in the month
when there was not a thunderstorm somewhere in the region. So,
although most stations had monthly totals below normal, some
isolated stations had much above normal rainfall. On a
state-by-state basis, this was most marked in North Carolina, where
Andrews, in the mountains, had 10.7 in (272 mm), or 193% of normal,
while Washington, NC, on the coast, had 0.15 in (4 mm), 3% of
normal. Other notable dry stations include Atlanta, GA with 0.58 in
(15 mm) or 16% of normal, Greenville-Spartanburg, SC with 3% of
normal and the driest June on record, and Anniston, AL with 4%.

After being free of "Exceptional Drought" since the middle of
March, the low rainfall brought a return to this category for parts
of the region during June. By the end of the month upstate South
Carolina and western North Carolina were once again involved. The
area with the somewhat less severe "Extreme Drought" expanded to
include areas in northeast Georgia and broader areas of North and
South Carolina. Only small areas of northern Virginia, south
Alabama and central Florida were not in dry conditions. The weather
pattern during June 2008 was dominated by an upper level ridge that
steered precipitation-producing systems west and north of the
region. These systems, however, pushed several relatively weak cold
fronts through the area during the month and these provided
isolated to scattered thunderstorms. Although we do not expect too
many tornadoes in June in the Southeast, this year the number (18
tornadoes) was near average, with the flow pattern ensuring that
most of them were associated with outbreaks at the northern edge of
the region.

SOUTH REGION DROUGHT

As noted by the Southern
Regional Climate Center, in general, precipitation for the
month of June was below normal in most of the Southern Region. As
expected for this time of year, there were small pockets of
near-normal to above-normal precipitation. These areas were
scattered about the region, but concentrated more in the west
central area of Texas. The only main portion of the region that
experienced above normal precipitation was in northwestern Arkansas
and northeastern and southeastern Oklahoma. In that area, monthly
totals ranged from 130 to 200 percent of normal.

In the Southern Region, drought conditions during June changed
slightly from last month, being predominant in three corners of the
region: western
Oklahoma and northeastern Texas, southern Texas, and eastern
Tennessee. Since last month, a small patch of moderate drought
has been identified in east central Louisiana along the Mississippi
border. This area makes up approximately 9% of the state of
Louisiana and just over 2% of Mississippi. Although the extent of
drought has not changed much from last month in western Oklahoma,
conditions have worsened. As of July 1, 2008, the entire panhandle
was in a state of drought, with the two western-most counties
showing D4, or exceptional drought conditions — the highest
level of drought on the U.S. Drought Monitor. In addition, there
was a narrow band of moderate drought in the southeastern portion
of the state extending from Greer County to Marshall County.

In the case of Tennessee, drought was still restricted to the
eastern half of the state during June, with little change to the
amount of areal extent from May. Similar to Oklahoma, however,
drought conditions in eastern Tennessee worsened slightly. At the
end of May, only 37% of the state observed moderate drought or
worse, with one tenth of the state observing severe drought
conditions. By July 1, approximately one third of Tennessee was in
severe drought, with another 15% of the state in moderate
drought.

The most dramatic changes in drought were observed in Texas, where
approximately 65% of the area was in a state of moderate drought or
worse. A more significant change from May, however, was the amount
of exceptional drought in Texas. At the end of May, only two small
pockets (approximately 1.5% of the state) of exceptional drought
were present, with a small area being located in the northern
panhandle, and a second small area in the south central counties.
By the end of June, much of the southern counties of the state were
experiencing extreme or exceptional drought conditions. Extreme
drought extended as far west as Edwards and Kinney Counties, and as
far east as Galveston. It also extended as far south as Cameron
County and as far north as Milam County. In total, approximately
one quarter of the state was experiencing severe drought or worse,
with approximately 13% of the state in exceptional drought
conditions. In Texas, exceptional drought was observed in Dallam
and Sherman counties in the northern panhandle, and in
approximately a dozen counties in the south central portions of the
state, centered about Gonzales County.

As a result of the drought conditions in Texas, outdoor burn bans
have been declared in many counties throughout the state. Because
conditions continued to be dry, KSAT news in San Antonio reported
that water restrictions were in effect for 58 public water systems
across the state.

As noted by the High Plains
Regional Climate Center, areas of much wetter than normal
(150%+) and much drier than normal (50% and below) precipitation
existed across the region. Areas well below normal precipitation
occurred in the majority of Colorado and Wyoming with other areas
including western Kansas and northeastern Nebraska. Drought
conditions continued to persist over many of the same areas as May
with one marked area of great improvement. The extreme drought
conditions (D3) of North Dakota improved greatly and were reduced
to a large area of D0 (abnormally dry) and D1 (moderate drought) in
the west with a smaller area of D2 (severe drought) along the
western border. Drought conditions no longer existed in eastern
North Dakota. Northwestern Nebraska also dropped from D2 drought
condition to D1 during June. Drought through the rest of the region
remained the same with some increased D3 areas along the southern
portions of the Colorado-Kansas border.

WESTERN DROUGHT

As summarized by the Western
Regional Climate Center, precipitation was characteristically
sparse to nonexistent in the Southwest and most of the
intermountain region. Pockets of Montana and the Pacific Northwest
had above normal precipitation for the month, but otherwise most of
the West had below normal rainfall. Of special note, the governor
of California proclaimed a statewide drought after 2 consecutive
years of below normal rainfall, especially the case from late
winter to early summer. At the end of the precipitation season
widely used in California (July 1, 2007 to June 30, 2008), much of
the state had received only 75 percent of normal, after a promising
start. The previous year had 20-60 percent of normal, so in some
cases impacts have accumulated. Many locations in the state have
had less rain in the past 24 months than their annual average.

The cool conditions over the past three months have greatly reduced
the melt rate of the snowpack
in the Pacific Northwest. On June 30, the NRCS Mount Hood Test Site
Snotel station at 5400 ft elevation (1646 m) in the Oregon Cascades
reported 122.1 inches (3101 mm) of precipitation since October 1,
with 50.3 inches (128 cm) of water content in the snow pack
remaining on the ground. Other large totals included 175 inches
(4445 mm) of precipitation since Oct 1 at Blazed Alder, OR, and
70.8 inches of water content (180 cm), nearly six feet, in the
remaining soggy snowpack at Paradise Ranger Station on Mount
Rainier in Washington. Many streams
were running at all time high flows for this time of year in
western Washington.

From the 19th to the 22nd southern California suffered through
record heat. The 21st brought dry lightning to much of the northern
half of the state sparking over 800 fires and producing very thick
smoke. Unhealthy air quality persisted through the end of the month
in numerous California, Oregon, and Nevada locations.

Alaska: According to National Weather
Service reports (from information provided by Audrey Rubel at NOAA
NWS Alaska Region Headquarters), June is normally one of the drier
months of the year for the Alaska panhandle, but June 2008 was
significantly drier than normal in many areas. The panhandle was
drier than normal in northern and central locations, while southern
locations were above normal for precipitation. The little rain that
fell was distributed in a weak bimodal fashion during the first and
last weeks of the month. Significant rain fell during the first
week in northern portions of the panhandle, which helped alleviate
the ongoing and significant precipitation deficit in this area.
However, the far northern panhandle still lagged far below normal
(15 inches/380 mm) in terms of the year-to-date accumulated
precipitation. Rainfall amounts in the panhandle were 25%-54% below
normal during the month. In central Alaska, June 2008 rainfall
amounts were highly variable due to the scattered nature of most
precipitation. The interior of Alaska experienced unusually low
wildfire activity for June. At the end of the month, Fairbanks had
yet to experience even a hint of smoke this summer. Despite the
presence of boreal summer, snow was recorded at several locations
in Alaska during June.

NORTHEAST DROUGHT

As noted by the Northeast
Regional Climate Center, rainfall totals were quite variable
throughout the Northeast, especially in Maine. Totals in the
Vacation State ranged from 2 inches (51 mm) along the coast to over
9 inches (229 mm) in the northwest portion of the state. Overall,
the Northeast averaged 4.62 inches (117 mm) of rainfall, which was
113% of normal. Vermont, New Hampshire and Maine were the wettest
states, with 152%, 144% and 143% of the 30-year normal,
respectively. New Jersey and Delaware were the driest states in the
region, averaging 75% and 80% of the normal June precipitation. By
month's end, the U.S. Drought Monitor indicated abnormally dry
conditions in Rhode Island, southeastern Massachusetts, southern
West Virginia, eastern Long Island, NY, and along the
Pennsylvania-New Jersey-New York border.

The graph below left shows December-June precipitation from
1896-2008 for Texas division 7. According to preliminary data,
December 2007-June 2008 ranked as the fourth driest December-June
in the 114-year record. The graph below right also shows the
1896-2008 December-June precipitation for Texas division 7 (annual
values in light blue, 5-year weighted average in dark blue). The
most striking multi-year anomaly in this record is the 1950s
drought (indicated with the orange bar), which had seven
consecutive years (1950-1956) with below-normal December-June
precipitation.

The graph above right
also shows a 344-year tree-ring record (1652-1995; annual values in
light red; 5-year smoothed values in dark red) that corresponds
well to the variability in December-June precipitation. This record
is a composite of six post oak (Quercus stellata) tree-ring
chronologies from south Texas (Therell, 2000). The correlation
between the annual values of the tree-ring record and December-June
precipitation is 0.748, indicating a high degree of shared
variance. The tree-ring record captures both the inter-annual and
decadal-scale variability of the observed precipitation record very
well.

The tree-ring record, as a proxy for precipitation, can put the
December-June precipitation variability of the last century in
south central Texas into a much longer perspective. In the
approximately 250-years prior to 1896, the tree-ring record shows
about a dozen individual years that likely had very low
December-June precipitation similar to the lowest values in the
past century, such as 2008. Looking at multi-year droughts, the
1950s drought appears to have been matched and possibly exceeded by
one that occurred in the early 1700s (red bar), in which the
ring-width index was below average for seven years in a row
(1711-1717) and the cumulative ring-width anomaly for those seven
years was slightly lower than for 1950-1956.

While the recent dryness in south central Texas has been extreme,
the tree-ring record indicates that it is an uncommon but not
extraordinary drought event — the type that has occurred
several times per century since at least 1650.

Resources:

Divisional climate data, including precipitation for Texas
Division 7 as shown above, can be obtained from
NCDC.